//MD5.cpp  

  
/* interface header */  
#include "md5.h"  
  
/* system implementation headers */  
#include <stdio.h> 
#include <cstring> 
  
  
// Constants for MD5Transform routine.  
#define S11 7  
#define S12 12  
#define S13 17  
#define S14 22  
#define S21 5  
#define S22 9  
#define S23 14  
#define S24 20  
#define S31 4  
#define S32 11  
#define S33 16  
#define S34 23  
#define S41 6  
#define S42 10  
#define S43 15  
#define S44 21  
  
///////////////////////////////////////////////  
  
// F, G, H and I are basic MD5 functions.  
inline MD5::uint4 MD5::F(uint4 x, uint4 y, uint4 z) {  
    return x&y | ~x&z;  
}  
  
inline MD5::uint4 MD5::G(uint4 x, uint4 y, uint4 z) {  
    return x&z | y&~z;  
}  
  
inline MD5::uint4 MD5::H(uint4 x, uint4 y, uint4 z) {  
    return x^y^z;  
}  
  
inline MD5::uint4 MD5::I(uint4 x, uint4 y, uint4 z) {  
    return y ^ (x | ~z);  
}  
  
// rotate_left rotates x left n bits.  
inline MD5::uint4 MD5::rotate_left(uint4 x, int n) {  
    return (x << n) | (x >> (32-n));  
}  
  
// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.  
// Rotation is separate from addition to prevent recomputation.  
inline void MD5::FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {  
    a = rotate_left(a+ F(b,c,d) + x + ac, s) + b;  
}  
  
inline void MD5::GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {  
    a = rotate_left(a + G(b,c,d) + x + ac, s) + b;  
}  
  
inline void MD5::HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {  
    a = rotate_left(a + H(b,c,d) + x + ac, s) + b;  
}  
  
inline void MD5::II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {  
    a = rotate_left(a + I(b,c,d) + x + ac, s) + b;  
}  
  
//////////////////////////////////////////////  
  
// default ctor, just initailize  
MD5::MD5()  
{  
    init();  
}  
  
//////////////////////////////////////////////  
  
// nifty shortcut ctor, compute MD5 for string and finalize it right away  
MD5::MD5(const std::string &text)  
{  
    init();  
    update(text.c_str(), text.length());  
    finalize();  
}  
  
//////////////////////////////  
  
void MD5::init()  
{  
    finalized=false;  
  
    count[0] = 0;  
    count[1] = 0;  
  
    // load magic initialization constants.  
    state[0] = 0x67452301;  
    state[1] = 0xefcdab89;  
    state[2] = 0x98badcfe;  
    state[3] = 0x10325476;  
}  
  
//////////////////////////////  
  
// decodes input (unsigned char) into output (uint4). Assumes len is a multiple of 4.  
void MD5::decode(uint4 output[], const uint1 input[], size_type len)  
{  
    for (unsigned int i = 0, j = 0; j < len; i++, j += 4)  
        output[i] = ((uint4)input[j]) | (((uint4)input[j+1]) << 8) |  
        (((uint4)input[j+2]) << 16) | (((uint4)input[j+3]) << 24);  
}  
  
//////////////////////////////  
  
// encodes input (uint4) into output (unsigned char). Assumes len is  
// a multiple of 4.  
void MD5::encode(uint1 output[], const uint4 input[], size_type len)  
{  
    for (size_type i = 0, j = 0; j < len; i++, j += 4) {  
        output[j] = input[i] & 0xff;  
        output[j+1] = (input[i] >> 8) & 0xff;  
        output[j+2] = (input[i] >> 16) & 0xff;  
        output[j+3] = (input[i] >> 24) & 0xff;  
    }  
}  
  
//////////////////////////////  
  
// apply MD5 algo on a block  
void MD5::transform(const uint1 block[blocksize])  
{  
    uint4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];  
    decode (x, block, blocksize);  
  
    /* Round 1 */  
    FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */  
    FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */  
    FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */  
    FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */  
    FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */  
    FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */  
    FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */  
    FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */  
    FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */  
    FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */  
    FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */  
    FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */  
    FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */  
    FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */  
    FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */  
    FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */  
  
    /* Round 2 */  
    GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */  
    GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */  
    GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */  
    GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */  
    GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */  
    GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */  
    GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */  
    GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */  
    GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */  
    GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */  
    GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */  
    GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */  
    GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */  
    GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */  
    GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */  
    GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */  
  
    /* Round 3 */  
    HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */  
    HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */  
    HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */  
    HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */  
    HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */  
    HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */  
    HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */  
    HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */  
    HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */  
    HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */  
    HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */  
    HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */  
    HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */  
    HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */  
    HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */  
    HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */  
  
    /* Round 4 */  
    II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */  
    II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */  
    II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */  
    II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */  
    II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */  
    II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */  
    II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */  
    II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */  
    II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */  
    II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */  
    II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */  
    II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */  
    II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */  
    II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */  
    II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */  
    II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */  
  
    state[0] += a;  
    state[1] += b;  
    state[2] += c;  
    state[3] += d;  
  
    // Zeroize sensitive information.  
    memset(x, 0, sizeof x);  
}  
  
//////////////////////////////  
  
// MD5 block update operation. Continues an MD5 message-digest  
// operation, processing another message block  
void MD5::update(const unsigned char input[], size_type length)  
{  
    // compute number of bytes mod 64  
    size_type index = count[0] / 8 % blocksize;  
  
    // Update number of bits  
    if ((count[0] += (length << 3)) < (length << 3))  
        count[1]++;  
    count[1] += (length >> 29);  
  
    // number of bytes we need to fill in buffer  
    size_type firstpart = 64 - index;  
  
    size_type i;  
  
    // transform as many times as possible.  
    if (length >= firstpart)  
    {  
        // fill buffer first, transform  
        memcpy(&buffer[index], input, firstpart);  
        transform(buffer);  
  
        // transform chunks of blocksize (64 bytes)  
        for (i = firstpart; i + blocksize <= length; i += blocksize)  
            transform(&input[i]);  
  
        index = 0;  
    }  
    else  
        i = 0;  
  
    // buffer remaining input  
    memcpy(&buffer[index], &input[i], length-i);  
}  
  
//////////////////////////////  
  
// for convenience provide a verson with signed char  
void MD5::update(const char input[], size_type length)  
{  
    update((const unsigned char*)input, length);  
}  
  
//////////////////////////////  
  
// MD5 finalization. Ends an MD5 message-digest operation, writing the  
// the message digest and zeroizing the context.  
MD5& MD5::finalize()  
{  
    static unsigned char padding[64] = {  
        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  
    };  
  
    if (!finalized) {  
        // Save number of bits  
        unsigned char bits[8];  
        encode(bits, count, 8);  
  
        // pad out to 56 mod 64.  
        size_type index = count[0] / 8 % 64;  
        size_type padLen = (index < 56) ? (56 - index) : (120 - index);  
        update(padding, padLen);  
  
        // Append length (before padding)  
        update(bits, 8);  
  
        // Store state in digest  
        encode(digest, state, 16);  
  
        // Zeroize sensitive information.  
        memset(buffer, 0, sizeof buffer);  
        memset(count, 0, sizeof count);  
  
        finalized=true;  
    }  
  
    return *this;  
}  
  
//////////////////////////////  
  
// return hex representation of digest as string  
std::string MD5::hexdigest() const  
{  
    if (!finalized)  
        return "";  
  
    char buf[33];  
    for (int i=0; i<16; i++)  
        sprintf(buf+i*2, "%02x", digest[i]);  
    buf[32]=0;  
  
    return std::string(buf);  
}  
  
//////////////////////////////  
  
std::ostream& operator<<(std::ostream& out, MD5 md5)  
{  
    return out << md5.hexdigest();  
}  
  
//////////////////////////////  
  
std::string md5(const std::string str)  
{  
    MD5 md5 = MD5(str);  
  
    return md5.hexdigest();  
}  

Napi::Value CalculateMD5(const Napi::CallbackInfo& info) {
  Napi::Env env = info.Env();

  if (info.Length() < 1 || !info[0].IsString()) {
    Napi::TypeError::New(env, "String argument expected").ThrowAsJavaScriptException();
    return env.Undefined();
  }

  Napi::String input = info[0].As<Napi::String>();
  const std::string inputStr = md5(input.Utf8Value());
  
  return Napi::String::New(env, inputStr);
}

Napi::Object Init(Napi::Env env, Napi::Object exports) {
  exports.Set(Napi::String::New(env, "calculateMD5"), Napi::Function::New(env, CalculateMD5));
  return exports;
}

NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)